What is the future of WMDs and will the threat of them ever be negated?
While we cannot know what the future will hold, it seems at this point safe to say that states (and non-state actors such as terrorists) will continue to seek WMD and that the threat of WMD will not be negated in the foreseeable future.
States and others will continue to seek WMD because WMD confer power and some degree of status. While we do not like to admit it, North Korea has benefitted from having developed even a rudimentary nuclear program. The country can use the threat of its weapons to force other countries to take it more seriously. Its nuclear weapons help to allow it to act in ways that irritate its neighbors without any real fear of military repercussions.
There are at least two other factors that will probably allow WMD to continue to exist in the future. First, it is likely that technology will make WMD cheaper and easier to make. Today, it is hard for most countries to get up the technological know-how and the resources to create a WMD program. As technology advances, these start-up costs will probably drop, making WMD affordable for more countries. Second, as is discussed in the link below, the power of the Western countries may be declining, making it harder for them to enforce the nonproliferation regime that they set up decades ago when they had a stronger hold on power in the world. If WMD get cheaper and if the countries that try to stop their spread get weaker, they are likely to continue to exist and they may even proliferate.
If we cannot prevent countries from getting WMD, the only other way to negate their threat is by devising ways to defeat them technologically. This may someday be possible, but it is not going to be in the near future. For all the money and effort that the US has put into missile defense systems, we have yet to invent anything that would afford us sufficient security against attack by nuclear missiles. Moreover, nuclear missiles may be the WMD that are easiest to defend against. Chemical or biological weapons could be delivered in ways that would be much more stealthy than a rocket. It would be very hard to defend, for example, against dedicated attackers who wanted to carry out chemical weapons attacks such as the Aum Shinrikyo in Tokyo in 1995. Therefore, it seems like it would be almost impossible to create technological defenses that would negate the threat of WMD.
For these reasons, it seems likely that WMD have a future in our world and that we will not be free of their threat any time soon.